package com.common.swagger.gateway;

import org.springframework.cloud.gateway.config.GatewayProperties;
import org.springframework.cloud.gateway.route.RouteLocator;
import org.springframework.context.annotation.Primary;
import org.springframework.stereotype.Component;
import org.springframework.util.CollectionUtils;
import springfox.documentation.swagger.web.SwaggerResource;
import springfox.documentation.swagger.web.SwaggerResourcesProvider;

import javax.annotation.Resource;
import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;

@Primary
@Component
public class SwaggerProvider implements SwaggerResourcesProvider {

    public static final String SWAGGER_URL = "/v2/api-docs";

    @Resource
    private RouteLocator routeLocator;

    @Resource
    private GatewayProperties gatewayProperties;

    @Override
    public List<SwaggerResource> get() {
        List<SwaggerResource> resources = new ArrayList<>();
        List<String> routeHosts = new ArrayList<>();
        // 由于我的网关采用的是负载均衡的方式，因此我需要拿到所有应用的serviceId
        // 获取所有可用的host：serviceId
        routeLocator.getRoutes().filter(route -> route.getUri().getHost() != null)
                .filter(route -> {
                    if (CollectionUtils.isEmpty(getExcludes())) {
                        return true;
                    }
                    return !getExcludes().contains(route.getUri().getHost().toLowerCase());
                })

                .subscribe(route -> routeHosts.add(route.getUri().getHost()));

        // 记录已经添加过的server，存在同一个应用注册了多个服务在nacos上
        Set<String> dealed = new HashSet<>();
        routeHosts.forEach(instance -> {
            // 拼接url，样式为/serviceId/v2/api-info，当网关调用这个接口时，会自动通过负载均衡寻找对应的主机
            String url = "/" + instance.toLowerCase() + SWAGGER_URL;
            if (!dealed.contains(url)) {
                dealed.add(url);
                SwaggerResource swaggerResource = new SwaggerResource();
                swaggerResource.setUrl(url);
                swaggerResource.setName(instance);
                resources.add(swaggerResource);
            }
        });
        return resources;
    }

    /**
     * 网关应用名称
     */
    public List<String> getExcludes() {
        List<String> excludes = new ArrayList<>(2);
        excludes.add("gateway-server");
        excludes.add("authority-server");
        return excludes;
    }
}